Hello everyone!
Just need some advice on what to look for when purchasing lens for the Ciro-Flex tlr model E camera I just got on E-bay. What sizes, models, will fit it. I have never shot a photo in medium format and need all advice in plain english

If the camera is intact, it has a viewing and a taking lens, neither of which can be interchanged. There used to be supplementary lens sets of Galilean design that afforded modest wide-angle and long-focus capability for twin-lens reflex cameras, and of course close-up lenses. I've had the pleasure of handling a "Ciro-Flex," but I never owned one, and so can't speak to the diameter and attachment method of front-lens accessories.

The camera does not accept interchangeable lenses. What you have is what you got. Look for a series VI adapter of the diameter of the OD of the lens. Then, you can use series VI filters, close up lenses, etc. When using close up lenses (ie: Kodak Portra lenses), you will need to slip the adapter/lens onto the viewing lens to focus, then slip it onto the taking lens to shoot.

Another way to go would be to work with a machinist, have him / her machine a slip-fit adapter ring for the taking lens. Have that adapter ring able to accept some modern filters, perhaps have a 49mm thread on the end. I'm doing that on my Model F Ciro-Flex, because the taking lens is a different diameter from the taking lens on other model Ciro-Flexes.

But since you have an E-model, the Series VI filter system is probably the cheapest way to go, and they are often available on Ebay.

There were a number of ingenious accessories available for twin-lens reflexes in the '50s and '60s.

One of the niftiest was a device from Mamiya designed to simplify work with close-up lenses. It consisted of a little platform with tripod screw, to hold the camera, that rode up and down on a scissors assembly whose vertical travel matched the separation between viewing and taking lens. That assembly was, in turn, fixed to a sturdy base with tripod socket.

You could use a pair of close-up lenses, one for the viewing and the other, for the taking lens. With the platform lowered, you focused; then you raised the platform to shoot.

If one were not doing anything much, some rainy weekend, it might be fun to make such a thing for a "Ciro-Flex."

I've collected, no.... I don't like that term because I bought the stuff to use.

I've amassed a few Ciro-Flex odds and ends that I think are cool. Not selling them, I'm using them. Series VI filter holders, a lens hood, a flash, and a set of Spiratone magnifying lenses for it. Allows really close-up portrait work, though the depth of field is really shallow. One goes on each lens, and then you just use it as you would normally.

Works really well. I continue to be amazed at how well this old stuff can work.